A keyboard is an indispensable device to modern people for using a computer. A lot of keys are disposed on a keyboard for a user to press to enter an instruction.
With improvement to keyboards, currently, keyboards having backlight modules, which alternatively, are usually referred to as luminous keyboards, have appeared, such keyboards are used in indoor lighting environments (such as offices and rooms), and light rays that travel upward from bottoms of the keyboards to pass through each key can be obviously recognized by human eyes, so as to present visual effects.
However, because light sources disposed on the bottoms of the keyboards emit light rays having a small divergence angle, a place right above a light source would emit light rays and render high brightness, while a periphery distant from a light source render very low brightness because of not being irradiated by light rays. Further, consequently, a plurality of non-uniform bright and dark places would be presented on a surface of an entire keyboard, and vision of a user during operation would be affected, which is not expected by a designer. Therefore, a conventional luminous keyboard still needs to be improved.